VTG Stronglight 99 with smaller chainrings
 

Long story short, has anyone ever run, or know for sure if you can run a Stronglight 99 crankset double with a 40T or 42T outer chainring and a 30T or 32T inside chainring? In other words, use what is normally the inner chainring as the outer? I don't know why it wouldn't work, since the on the 99, the outer chainrings use the same 86 BCD to mount as the inner, but there may be something I'm not considering. I realize there are many other alternatives, but this is my cheapest solution to my problem.

I don't think there is any reason why this should not work. 86 bcd chainrings are available from Spa cycles in the UK.

The inner rings are usually not as nicely finished as the outers.

There may be an issue about counterboring of bolt holes, too.

As ​​​bikemig points out, Spa Cycles sells 86 BCD chainrings. That includes 40/42T outers and 30/32T inners, so you don't even have to think about using an inner as an outer: https://www.spacycles.co.uk/m2b0s149...l-40-50t-outer :thumb:

(But even if you swapped rings between inner and outer, it ought to work fine. Not having the counterbore on the outer face just means the head of the crank bolt will sit proud of the chainring. EDIT: I wouldn't flip a ring around to use the counterbores, for the potential issues John calls out in following posts.)

Sakae/SR and Takagi also made 86BCD cranks/chainrings. Check the Bay. They are usually cheaper than the Stronglights.

The teeth on Stronglight rings are centered with respect to the thickness of the ring, while those on Sakae Ringyo rings are offset slightly, with a ramp on what is intended to be the inner face of the ring. If you use what is designed to be a middle ring on a Sakae Ringyo crank as the outer ring instead, that ramp will be on the outside (unless you ignore the counterbore for the bolts and let the bolts stand pround of the ring face), and shifting will suffer.

Been there, done that.

Both very good points. I hadn't taken either into account. Appearance is very important on this particular build, so these may be a deal breakers. I am planning on just adding a 30T Stronglight from a triple to the existing Stronglight 40T, so I believe that would eliminate some of the other potential pitfalls.

But shifting won't be an issue if running a stronglight inner as an outer even if the bolts stick out, right? This is a problem with SR rings as they are offset? Or am I missing something?

The teeth are centered with Stronglight rings, so they can work as either outer or middle/inner rings. If you turn a middle/inner Sakae Ringyo ring to use as an outer, with the counterbore facing out for the bolts, the chain has a hard time climbing up to the outer ring.

I thought that was what you were saying but I just wanted to be clear.

Great info! Between you and T-mar and others, we have a wealth of knowledge at our disposal.

I have run a 99 with 28t inner ring and 44t or 45t outer. No problems, and I don't remember know whether the inner rings we're Stronglight or Sakae.

Sounds like it will definately fine work with Stronglight Chainrings, which is what I was planning on using anyway. I just need to see what it will actually look like before I decide this is the route I want to go, although I'm the only one who would ever notice the bolts. That or just build a another new-old bike just for hill climbing :)

Stronglight 99 with 28/40/45.
https://cimg9.ibsrv.net/gimg/bikefor...a960f79113.jpg

Thumpism, I like the way it looks without the unused outer holes on the outer ring.